Expression of Osteopontin and Cyclooxygenase-2 in relation to cellular proliferation, in non-tumor colonic mucosa, colonic adenomas and colon adenocarcinoma.

Abstract

Introduction: the participation of Cyclooxygenase-2 (COX-2) and Osteopontin has been postulated in the development of colon cancer, which play an important role in the progression and could be biomarkers for its prognosis, but their role remains controversial. Objective: to determine and to compare the expression of Osteopontin and COX-2 in non-tumor colonic mucosa, colonic adenomas and colon adenocarcinoma, in relation to the cell proliferation index. Methods: the immunohistochemical expression of COX-2, Osteopontin and Ki-67 in formalin fixed paraffin embedded tissue of non-tumor colonic mucosa, colonic adenomas and colon adenocarcinoma were determined and compared. Results: were included 65 cases: 19 of non-tumor colonic mucosa, 13 colonic adenomas and 33 colon adenocarcinomas. There was increased expression of Ki-67 in dysplastic and tumor cells. There was positive expression for COX-2 in adenomas (30.7%) and adenocarcinomas (27.3%), without significant difference between nontumor colonic mucosa, adenomas and adenocarcinoma (p = 0.888). Osteopontin showed more frequent positivity in adenocarcinomas (72.7%) and adenomas (84.6%) than in non-tumor mucosa (10.5%), (p = <0.0001), without significant differences in its expression between subtypes and grades of adenoma dysplasia, nor between grades of differentiation, extension and proliferation of adenocarcinomas. There was a significant association between Osteopontin expression and the cell proliferation index. No association was observed between the expression of COX-2 and Osteopontin (p = 0.96). Conclusions: Osteopontin overexpression in colon adenocarcinoma and adenomas in comparison with non-tumor colonic mucosa, and its significant relationship with the cell proliferation index, constitutes additional evidence of its possible participation in the colonic carcinogenesis process.